Defrost evincing devices

ABSTRACT

A defrost evincing device, which operates as a telltale temperature indicator for frozen packages or spaces maintained at low temperatures to indicate reliably the occurrence of even a transient thawing temperature which may have been followed by a re-freezing cycle. Such telltale indicating assemblies have been included for this purpose in frozen food packages and the like, and these generally comprise a capsule filled with a colored liquid such as colored water, which capsule ruptures upon the initial freezing of the package, leaving free the frozen coloring fluid for eventual flow upon the thawing of the frozen package. When this occurs, the flowing liquid may permeate an absorbent piece of paper or the like disposed in proximity to the capsule, which imparts distinctive color to the absorbent indicator, which is permanent and irreversible, to constitute evidence of the package having gone through at least one thawing cycle even if it was re-frozen subsequently. The instant invention aims to provide a rugged container for the colored fluid capable of sustaining heavy loads so that the same is fractured only upon freezing of the container rather than by any weight loadings to which the same may be subjected. Thereby assurance is had that when the absorbent indicator becomes distinctively colored, it is the result of the flow of the colored fluid upon the thawing of the frozen package, and not as a result of the fracture of the container in its initial state by the loadings imposed thereon. To ensure the fracture of the container by the expansive force of the freezing fluids, at least one of the walls thereof is of thinner cross-section than the load-bearing walls. Furthermore, a tension member is provided in the container, acting against the frangible wall, to assure an adequate fissure in the ruptured receptacle through which the colored fluid may flow towards the absorbent indicator.

United States Patent Szabo [451 Nov. 7, 1972 [54] DEFROST EVINCINGDEVICES [72] Inventor: Bela G. Szabo, 5138 Delford St.,

Pittsburgh, Pa. 15207 22 Filed: Aug. 19, 1970 211 Appl. No.: 64,986

[52] US. Cl ..73/358, 73/356, 99/192 TT, 116/1 14.5 [51] Int. Cl. ..G0lk11/08 [58] Field of Search ..73/358; 116/114 Y, 114.5; 99/192 TT; 13/356[56] References Cited UNITED STATES PATENTS 3,437,070 4/1969 Campbell..73/358 2,823,131 2/1958 Power ..116/l14.5 3,521,489 7/1970 Finkelstein..73/358 3,177,843 4/1965 Geocaris ..116/1l4.5

Primary Examiner-Louis R. Prince Assistant Examiner-Denis E. CorrAttorney-Samuel Lebowitz [5 7 ABSTRACT A defrost evincing device, whichoperates as a telltale temperature indicator for frozen packages orspaces maintained at low temperatures to indicate reliably theoccurrence of even a transient thawing temperature which may have beenfollowed by a re-freezing cycle. Such telltale indicating assemblieshave been included for this purpose in frozen food packages and thelike, and these generally comprise a capsule filled with a coloredliquid such as'colored water, which capsule ruptures upon the initialfreezing of the package, leaving free the frozen coloring fluid foreventual flow upon the thawing of the frozen package. When this occurs,the flowing liquid may permeate an absorbent piece of paper or the likedisposed in proximity to the capsule, which imparts distinctive color tothe absorbent indicator, which is permanent and irreversible, toconstitute evidence of the package having gone through at least onethawing cycle even if it was re-frozen subsequently. The instantinvention aims to provide a rugged container for the colored fluidcapable of sustaining heavy loads so that the same is fractured onlyupon freezing of the container rather than by any weight loadings towhich the same may be subjected. Thereby assurance is had that when theabsorbent indicatorbecomes distinctively colored, it is the result ofthe flow of the colored fluid upon the thawing of the frozen package,and not as a result of the fracture of the container in its initialstate by the loadings imposed thereon. To ensure the fracture of thecontainer by the expansive force of the freezing fluids, at least one ofthe walls thereof is of thinner cross-section than the load-bearingwalls. Furthermore, a tension member is provided in the container,acting against the frangible wall, to assure an adequate fissure in theruptured receptacle through which the colored fluid may flow towards theabsorbent indica- 16 Claims, 11 Drawing Figures minimum 1 m2 3,702,011

SHEET 1 OF 2 t5 'INVENTOR ATTORNEY DEFROST EVINCING DEVICES Thisinvention relates to a defrost evincing device which may be used inconjunction with frozen packages of all types as well as refrigeratedchambers such as freezing boxes, refrigerated railway cars and trucks,etc. More particularly, the device is adapted for use in conjunctionwith packages subjectedto heavy loadings which, nevertheless, does notaffect its capability of affording a fine and sensitive indication ofany thawing which may have taken place between the time of the originalfreezing of the package and the time of use by the consumer.

It is the object of the present invention to provide highly rugged andeconomical telltale indicators for frozen packages or containersmaintained under subfreezing conditions, which respond to a lowering ofthe temperature to a predetermined level for indicating reliably theincidence of said temperature level which may affect deleteriously thecontents of the packages which may be food, such as frozen meats orfish, chemicals, pharmaceuticals or other materials which are desired tobe maintained at freezing temperatures until they are ultimately used.

It is the aim of the present invention to improve upon such frozen foodindicators of the type disclosed in U.S. Pat. No. 3,177,843, Apr. 13,1965, which makes use of a frangible capsule filled with a coloredliquid medium which, upon freezing, results in the rupture of thecapsule and which, upon lowering of the temperature permits the coloredliquid to melt and to provide a permanent indication that it has gonethrough a melting stage, despite the fact that the package may have beenre-frozen subsequently.

It is another object of the invention to render readily visible theoccurrence of a thawing cycle no matter where the indicator might belocated. Its capability of withstanding high pressures and loadingsprecludes false indications arising from initial ruptures attributableto heavy loading pressures, before the freezing of the goods with theindicators therein is executed.

Other objects and purposes will appear from the detailed description ofthe invention following hereinafter, taken in conjunction with theaccompanying drawings, wherein FIG. 1 is a top plan view of oneembodiment of the defrost evincing device in accordance with theinvention;

FIG. 2 is a vertical sectional view along line 2-2 of FIG. 1;

FIG. 3 is a horizontal sectional view along line 3-3 of FIG. 2;

FIG. 4 is a top plan view of a second embodiment of the device encasedin a transparent water-repellent envelope;

FIG. 5 is a vertical sectional view along line'5-5 of FIG. 4;

FIG. 6 is a top plan view of a third embodiment of the device, partly insection;

FIG. 7 is a vertical sectional view along line 7-7 of FIG. 6;

FIG. 8 is an end view of FIG. 7;

FIG. 9 is a vertical sectional view of the device shown in FIGS. 6 to 8,encased in a water-repellent jacket, similar to FIG. 5;

FIG. 10 is a graphical representation of the thickness of the thin wallsrelative to the volumetric capacity of the containers, to attainreliable ruptures of the walls as the containers filled with coloredwater pass through the freezing point; and

FIG. 11 is a graphical representation of the optimum ratios of theaverage thicknesses of the thin walls to the thick walls of thecontainers.

In the drawings are shown several embodiments of defrost evincingdevices which may be embedded with material to be frozen, such as meatsand fish, or which may be inserted in packages containing such material,to provide a reliable indication that once the material has been frozenit is maintained in this frozen state until it reaches the consumer.Such indicators may be used in conjunction with FDA. or U.S.D.A.inspection stamps, to guarantee the maintenance of the quality ofproducts which are packaged for shipment by a producer for ultimateconsumption by the consumer, with no possibility of deterioration inconsequence of a thawing of the material or the packages in the courseof their transit from the producer to the consumer.

The defrost indicating device in accordance with the invention makes useof water tinted with a certified food coloring to assure the maintenanceof freezing temperature of approximately 32 F. If other temperatures areto be guaranteed,the solutions may be varied to control the point atwhich the indicating mass passes from the solid frozen state to theliquid state.

The indicators in accordance with the invention are characterized bytheir capability of withstanding high pressures and heavy loads, so thatthere is no possibility of rupture of these containers in the course ofpiling the packages on top of each other in the course of their initialassembly for freezing, as might be the case by the use of indicators forfrozen food packages as shown in the above-mentioned US. Pat. No.3,177,843. However, the containers are provided with at least one thinwall that is affected by the expansive force of the freezing water tocause the wall to fracture, so that upon the thawing of the indicatorthe liquid may flow from the container to produce a visible indicationof the occurrence of the thawing condition. While the load-bearingsupporting walls of the indicating container are sufficiently heavy towithstand pressures of 500 pounds or thereabouts, produced by the pilingup of packages of unfrozen products such as meats or seafoods, thecontainer must include at least one wall of lesser thickness which isshielded from any substantial load-bearing function so that it may befractured by the expansive force of the liquid which fills thecontainer, which in the case of water expands about I l to 12 percent,when it passes through the freezing cycle. Therefore, it is necessarythat the thin walls be at least half the thickness of the load-bearingwalls.

In the light of the above requirements, FIG. 1 shows a cylindricalcontainer C which preferably is molded of a rigid transparent syntheticplastic material such as polystyrene having a relatively thickperipheral wall 1 and a thin circular base wall 2. The container isadapted to be filled completely with a tinted fluid medium F, whichpreferably may be water colored with an edible and certified foodcoloring. A cover 3 for the cylindrical container is sealed to the top 4of the lateral wall 1 of the fluid filled container, preferably by meansl06005 OllZ of heat generated by ultrasonic energy. The cover 3 isprovided with a central thinner wall portion 5 which overlies the bodyof liquid F within the container.

A tension rod 7 may be molded integrally with the base 2 of thecontainer. This tension rod may be of frusto-conical formation with thefree end thereof extending to the inner surface of the cover. The rod 7is preferably of a height slightly greater than'the lateral the tintedwater, causes one or both walls 2 and 5 to be fractured in consequenceof the freezing of the body of water within the container. The ruptureof the walls permits the passage of the fluid medium from the interiorof the container if the fluid goes througha melting cycle. The provisionof the tension rod 7 assures a sufficiently distinct fissure in thefractured wall of thinner cross-section when the fluid melts.

In some instances the flow of the tinted fluid from within the containermay be detected readily by the presence of an irregular amount of thetinted material in the vicinity of the indicator amidst the materialwhich had been frozen. Thus, a green tinted liquid would be readilyvisible in a package of meat. Conversely, a crimson tinted liquid wouldbe readily visible in a package of frozen vegetables. In some instancesthe intermixture of the frozen material and the indicating medium wouldnot be objectionable. However, in order to define the indication moreaccurately, the base 2 and cover 3 may be provided with recesses 6 and6' for receiving discs of absorbent material such as filter paper 8 and9, respectively, which serve to absorb the tinted fluid F when the sameis melted.

In order to preclude any possibility of contamination of the frozenmaterial by the indicating substance, the container C, with orwithoutthe absorbent discs 8 and 9, resting within the recesses 6,6 of the baseand cover, may be encased within a flexible envelope 10 of thin plasticsheeting such as polyethylene, cellophase, or the like. The envelope 10would serve to contain the indicating fluid both in the frozen-statewith the ruptured thin walls, or inthe thawed state after the fluid isabsorbed totally or only partially by the indicating discs 8 and 9.Theenvelope may also include an instruction card or advertising material.

cation of ultrasonic energy to the marginal edges of the cover. Inthiscase as well, the indicating units are capable of withstanding highweight loadings, so that the inclusionthereof in packages gives rise tono danger of them rupturing accidentally before the freezing operation.After the material to be frozen, with the indicators interspersedtherethrough, pass through the freezing cycle, the block of tintedliquid F exerts its expansive forces against the end walls 14 of thecontainer to fracture them andto provide a path for the flow of thetinted liquid should it ever pass through a melting stage.

In order to assure the provision of distinct openings for the passage ofthe tinted fluid, a tensioning strap T may be inserted within thecontainer prior to the application and sealing of the cover thereon.This tensioning strap, which maybe of spring metal, is provided with amid-portion 16 which is pressed against the lower face of the cover 15and divergent arms 17, the ends of which press outwardly against thelower. edges of the thin walls 14. Thereby, the formation of a distinctcrevice in the thin walls of the container is assured.

In order to confine, as well as to render more distinct the flow of thetinted fluid F following its melting, a sheet of absorbent material 19may be wrapped around the container between the walls 13. Furthermore,the entire indicatingassembly may be confined within a transparentenvelope 20 in order to prevent any intermixture of the indicatorcomponents with the material in which the indicator assemblies may beinterspersed.

Of course, it is understood that the tension devices, such as the rod 7shown in the first embodiment, or the spring in the second embodiment,may be designed in many different ways, in dependence upon the specificcontours and arrangements of the walls of the indicator.

The defrost evincers in accordance with the invention may assume manydifferent shapes as long as they are provided with walls of differentialthickness which, on the one hand will impart sufficient strength to thecontainer to withstand high pressure loadings, and on the other hand,will have the capability of being ruptured by the expansive force of thefluid within the container when it passes through the freezing cycle.

The size of the indicators may vary in dependence upon the specificapplications in which they may be used. The smallest practical unitshown in FIG. 1 may have a diameter of about three-eighths inch, and athickness of one-fourth inch. These units can be molded economically byinjection molding procedures from various types of rigid plasticmaterials, for example polystyrene. FIG. 10 graphically illustrates thedifferent volumetric capacities of the indicating containers which maybe'molded to contain nearly one cubic inch of liquid. In the case ofindicators of small capacity, the thin walls, of necessity, must be ofsmaller dimension, so that the limited quantity of liquid may exert asufficient expansive force to effect the rupture of the container at thethin wall thereof. On the other hand, the thin walls may be ofsubstantially greater thickness when larger volumes of liquid are goingthrough the-freezing stage within containers of larger sizes. Asindicated in FIG. 10, tests have shown that reliable indicators may beproduced economically when the volumetric capacity of these range from0.05 to 0.9 cubic inches, in which case the thin walls may vary inthickness from approximately l0/l,000 to 58/1 ,000 of an inch. I

FIG. 11 graphically illustrates the optimum ratios of thicknesses of thethin walls which will render them rupturable by the expansion of thefreezing liquid to the average thicknesses of the thick walls which arecapable of bearing the required loads. The thin walls are at least halfthe thickness of the thick walls and tests have proven that mostsatisfactory results are had when these ratios approximate l to 3.

I claim:

1. A defrost evincing device comprising a cylindrical cartridgecontainer of hard synthetic plastic material filled with a fluidindicating medium consisting of an aqueous solution of food coloringmaterial, said container having walls of differential thickness of highload-bearing capabilities and comprising a thick peripheral wall and endwalls of small cross-section adapted to be ruptured by the expansiveforce of the frozen mass of said aqueous solution as it passes throughthe freezing cycle, a tension rod molded integrally with one of said endwalls and extending at least to the same height as said peripheral wallwith said opposite end wall ultrasonically heat-welded to the free edgeof said peripheral wall.

2. A device as set forth in'claim 1, wherein said tension rod is moldedcentrally of said base wall and is of tapered conical section andterminates slightly above the level of said peripheral wall.

3. A device as set forth in claim 1, wherein said end walls are providedwith recesses on the exterior thereof, and a sheet of absorbent materialwithin said recesses adapted to absorb the colored solution flowing fromsaid ruptured container when the solution passes through a thawingcycle.

4. A defrost evincing device comprising a container of substantiallyrectangular contour provided with a pair of opposed lateral supportingwalls and transversely extending walls of smaller cross-section thansaid supporting walls, said container being filled with a coloredaqueous solution, which upon freezing, experiences expansion and givesrise to an expansive force sufficient to rupture said walls of smallercrosssection, and means adjacent to said last-mentioned walls formaintaining the rupture distinct to enable the free flow of the solutionfrom the container in its defrosted state to indicate definitely theflow of the solution from said filled container, said last-mentionedmeans comprising a bowed spring extending between said transverse wallsfor forcing them outwardly upon their rupture by said expansive force.

5. A device as set forth in claim 4, wherein said spring is bowed in adownward direction with its midportion pressing against the inner faceof the top of said container while its edges press against the lowermargins of said transverse walls.

6. A device as set forth in claim 5, including a sheet of absorbentmaterial wrapped around the top, bottom and end walls of said containerbetween said lateral supporting walls.

7. A device as set forth in claim 6, including a moisture-impermeabletransparent envelope of flexible plastic sheet material encasing saidfilled container.

8. A defrost evincing device highly resistant to physical shocks andheavy weight loadings, comprising a unitary integrally sealed containerof only rigid molded synthetic plastic material, ranging in volume from0.5 to 0.9 cubic inches and filled completely with a fluid indicatingmedium, said container comprised of walls of differential thicknessincluding wall portions of great strength and at least one weaker wallportion responsivc to the expansive forces exerted thereon by thefreezing of said medium to effect the fracture of said container at saidlast-mentioned wall portion, to permit the free flow of said fluidindicating medium following the thawing thereof, said weaker wallportion ranging in thickness from approximately 10 to 58 thousandths ofan inch, and the thickness of the wall portions of great strength beingat least twice the thickness 'of said weaker wall portion.

9. A device as set forth in claim 8, including means adjacent to saidweaker wall portion for maintaining the rupture distinct to enable thefree flow of the fluid medium from the container in its thawed state toindicate definitely the flow of the fluid medium from said filledcontainer.

' 10. A device as set forth in claim 8, wherein said container is ofcylindrical contour having a strong and thick lateral wall with at leastone of the end walls constituting the weaker wall portion.

11. A device as set forth in claim 10, including means adjacent to saidweaker wall portion for maintaining the rupture distinct to enable thefree flow. of the fluid medium from the container in its thawed state toindicate definitely the flow of the fluid medium from said filledcontainer.

12. A device as set forth in claim 10, wherein said weaker end wallportion is provided with a recess on the exterior thereof, and a sheetof absorbent material within said recess adapted to absorb the fluidindicating medium flowing from said ruptured container when said mediumpasses through a thawing cycle.

13. A device as set forth in claim 8, wherein said container is ofrectangular contour provided with a pair of opposed lateral supportingwalls of great strength and transversely extending walls of smallercross-section to form weaker wall portions.

14. A device as set forth in claim 13, including means adjacent to saidtransversely extending walls for maintaining the rupture distinct toenable the free flow of the fluid medium from the container in itsthawed state to indicate definitely the flow of the fluid medium fromsaid filled container.

15. A defrost evincing device comprising a cylindrical cartridgecontainer of hard synthetic plastic material filled with a fluidindicating medium consisting of an aqueous solution of food coloringmaterial, said container having walls of differential thickness of highload-bearing capabilities and comprising a thick peripheral wall with atleast one of the end walls being of small cross-section adapted to beruptured by the expansive force of the frozen mass of said aqueoussolution as it passes through the freezing cycle, said lastmentioned endwall having a recess on the exterior thereof, a sheet of absorbentmaterial within said recess adapted to absorb the colored solutionflowing from said ruptured container when the solution passes through athawing cycle, and a moisture-impermeable transparent envelope offlexible plastic sheet material encasing said filled container.

synthetic transparent plastic material, having an internal volumetriccapacity for said fluid medium ranging in volume from 0.5 to 0.9 cubicinches and the thickness of the wall of thin cross-section ranging fromapproximately 10 to 58 thousandths of an inch.

1. A defrost evincing device comprising a cylindrical cartridgecontainer of hard synthetic plastic material filled with a fluidindicating medium consisting of an aqueous solution of food coloringmaterial, said container having walls of differential thickness of highload-bearing capabilities and comprising a thick peripheral wall and endwalls of small cross-section adapted to be ruptured by the expansiveforce of the frozen mass of said aqueous solution as it passes throughthe freezing cycle, a tension rod molded integrally with one of said endwalls and extending at least to the same height as said peripheral wallwith said opposite end wall ultrasonically heat-welded to the free edgeof said peripheral wall.
 2. A device as set forth in claim 1, whereinsaid tension rod is molded centrally of said base wall and is of taperedconical section and terminates slightly above the level of saidperipheral wall.
 3. A device as set forth in claim 1, wherein said endwalls are provided with recesses on the exterior thereof, and a sheet ofabsorbent material within said recesses adapted to absorb the coloredsolution flowing from said ruptured container when the solution passesthrough a thawing cycle.
 4. A defrost evincing device comprising acontainer of substantially rectangular contour provided with a pair ofopposed lateral supporting walls and transversely extending walls ofsmaller cross-section than said supporting walls, said container beingfilled with a colored aqueous solution, which upon freezing, experiencesexpansion and gives rise to an expansive force sufficient to rupturesaid walls of smaller cross-section, and means adjacent to saidlast-mentioned walls for maintaining the rupture distinct to enable thefree flow of the solution from the container in its defrosted state toindicate definitely the flow of the solution from said filled container,said last-mentioned means comprising a bowed spring extending betweensaid transverse walls for forcing them outwardly upon their rupture bysaid expansive force.
 5. A device as set forth in claim 4, wherein saidspring is bowed in a downward direction with its mid-portion pressingagainst the inner face of the top of said container while its edgespress against the lower margins of said transverse walls.
 6. A device asset forth in claim 5, including a sheet of absorbent material wrappedaround the top, bottom and end walls of said container between saidlateral supporting walls.
 7. A device as set forth in claim 6, includinga moisture-impermeable transparent envelope of flexible plastic sheetmaterial encasing said filled container.
 8. A defrost evincing devicehighly resistant to physical shocks and heavy weight loadings,comprising a unitary integrally sealed container of only rigid moldedsynthetic plastic material, ranging in volume from 0.5 to 0.9 cubicinches and filled completely with a fluid indicating medium, saidcontainer comprised of walls of differential thickness including wallportions of great strength and at least one weaker wall portionresponsive to the expansive forces exerted thereon by the freezing ofsaid medium to effect the fracture of said container at saidlast-mentioned wall portion, to permit the free flow of said fluidindicating medium following the thawing thereof, said weaker wallportion ranging in thickness from approximately 10 to 58 thousandths ofan inch, and the thickness of the wall portions of great strength beingat least twice the thickness of said weaker wall portion.
 9. A device assEt forth in claim 8, including means adjacent to said weaker wallportion for maintaining the rupture distinct to enable the free flow ofthe fluid medium from the container in its thawed state to indicatedefinitely the flow of the fluid medium from said filled container. 10.A device as set forth in claim 8, wherein said container is ofcylindrical contour having a strong and thick lateral wall with at leastone of the end walls constituting the weaker wall portion.
 11. A deviceas set forth in claim 10, including means adjacent to said weaker wallportion for maintaining the rupture distinct to enable the free flow ofthe fluid medium from the container in its thawed state to indicatedefinitely the flow of the fluid medium from said filled container. 12.A device as set forth in claim 10, wherein said weaker end wall portionis provided with a recess on the exterior thereof, and a sheet ofabsorbent material within said recess adapted to absorb the fluidindicating medium flowing from said ruptured container when said mediumpasses through a thawing cycle.
 13. A device as set forth in claim 8,wherein said container is of rectangular contour provided with a pair ofopposed lateral supporting walls of great strength and transverselyextending walls of smaller cross-section to form weaker wall portions.14. A device as set forth in claim 13, including means adjacent to saidtransversely extending walls for maintaining the rupture distinct toenable the free flow of the fluid medium from the container in itsthawed state to indicate definitely the flow of the fluid medium fromsaid filled container.
 15. A defrost evincing device comprising acylindrical cartridge container of hard synthetic plastic materialfilled with a fluid indicating medium consisting of an aqueous solutionof food coloring material, said container having walls of differentialthickness of high load-bearing capabilities and comprising a thickperipheral wall with at least one of the end walls being of smallcross-section adapted to be ruptured by the expansive force of thefrozen mass of said aqueous solution as it passes through the freezingcycle, said last-mentioned end wall having a recess on the exteriorthereof, a sheet of absorbent material within said recess adapted toabsorb the colored solution flowing from said ruptured container whenthe solution passes through a thawing cycle, and a moisture-impermeabletransparent envelope of flexible plastic sheet material encasing saidfilled container.
 16. A defrost evincing device comprising a containerfilled with a fluid indicating medium, said container having walls ofdifferential thickness of high load-bearing capabilities including awall of thin cross-section adapted to be ruptured by the expansivecharacteristics of said fluid medium incident to its transformation intoa frozen state, said container being formed of a hard synthetictransparent plastic material, having an internal volumetric capacity forsaid fluid medium ranging in volume from 0.5 to 0.9 cubic inches and thethickness of the wall of thin cross-section ranging from approximately10 to 58 thousandths of an inch.